Caption: Artificial sky. Male technician using an endoscope to examine an architectural model under an artificial sky. The sky consists of a hemispherical dome containing 640 individually controllable lamps. By selectively dimming the appropriate lamps, the brightness of different parts of the sky can be simulated. The dome also contains an artificial sun or heliodon (not seen here) to simulate direct sunlight. Any light conditions possible on Earth can be simulated. The system was developed by Donald Alexander of Cardiff University, Wales. The system is designed to help architects design buildings that make the maximum use of natural light thus saving energy.